1. Field of the Invention
Lens marking with particular reference to the coding of plastic artificial intraocular lenses (pseudophakoi) for establishing in each case a permanent record of particulars such as, for example, date and place of manufacture and monomer used.
2. Discussion of the Prior Art
In the manufacture, use, and sale of intraocularly implantable artificial lenses which are referred to in the art as pseudophakoi, it is essential for various reasons including law that a permanent record be made upon the article of particulars which may include date and place of manufacture and monomer used. Encoding with ciphers, i.e. seven characters and/or digits, affords countless separately identifiable bits of decodable information.
The application of such coding to the product, however, has heretofore presented serious problems for the following, to name a few, reasons:
The lenses of pseudophakoi are of necessity only approximately 5 mm in diameter and a center section of approximately 3 mm in diameter must be retained clear for visual use. Additionally, in each case, a substantial portion of the remaining approximately 1 mm margin must be utilized for attachment of the haptic section (lens clips) of the pseudophakos. Thus, there has been the serious problem of reducing character size of heretofore painted, leached, or engraved coding sufficiently to fit the space allowed while maintaining legibility. Additionally, painting, chemically leaching or engraving operations are not only difficult, tedious, time-consuming and expensive to perform particularly under the requirements of the aforesaid miniaturization of characters, but require special skills and equipment not always available or possible to make available at times and/or places of need.
Still further, painting, chemically leaching or engraving produce raised edges or depressions and systems of scratches or roughnesses which in any or all cases are potentially medically hazardous. Lens surface irregularities allow stagnation of body fluids and promote growth of micro-organisms. Surface interruptions or scratching caused by engraving can also be incipiative to lens material stressing or fissuring, either of which is potentially destructive to the lenses. Additionally, the inaesthetic readily discernable or undisguised nature of prior art coding by etching, leaching, or painting can be disconcerting to the observer of a pseudophakic and/or to the pseudophakic himself.
In view of the aforesaid and related drawbacks to prior art lens coding practices and with the urgent need for improvements in intraocular lens coding, it is an object of the present invention to provide a method for marking lenses which, in addition to being simple and economical to perform, will overcome the aforementioned and related problems and drawbacks of the prior art. More particularly, an object of the invention is to provide a method for marking lenses which, in addition to being simple and economical to perform, will provide readily decodable miniaturized caricatures undetectable to the naked eye, nondestructive to the lens article and nondisruptive of optimum surface smoothness but, on the other hand, readily discernable for interpretation either by direct reading or decoding with no more required than the aid of ordinary ophthalmological instruments.
Other objects and advantages of the invention will become more readily apparent from the following description.